The cytochrome P450 (CYP450) enzyme system is responsible for the biotransformation of drugs from active to inactive metabolites that are readily excreted by the body. Furthermore, the rapid metabolism of certain drugs by the CYP450 enzyme system can markedly alter their pharmacokinetic (PK) profile and can result in sub-therapeutic plasma levels of those drugs over time. In the area of anti-infective therapy, such as treating viral infections such as human immunodeficiency virus (HIV) infections, such sub-therapeutic drug plasma levels can lead to an increase in resistance of the virus.
Ritonavir (RTV) is a marketed HIV protease inhibitor (PI) that, due to its ability to inhibit the cytochrome P450 3A4 enzyme, is also used to “boost” the pharmacokinetic exposure of many co-administered anti-retrovirals. However, RTV is associated with clinically significant gastrointestinal and metabolic side effects including nausea, emesis, diarrhea, and dyslipidemia. Administering low doses of a compound with potent antiviral activity may also contribute to the selection of drug-resistant strains of HIV. A novel CYP3A4 inhibitor capable of boosting antivirals as effectively as RTV but devoid of antiviral activity and significant side-effects would offer significant advantages and therapeutic value in the treatment of those suffering from infection with the HIV virus. The present invention discloses compounds that are useful in the inhibition of the CYP450 enzyme system and may be used to boost the pharmacokinetic exposure of co-administered drugs, including anti-retrovirals. It also discloses pharmaceutical formulations comprising such compounds, methods of making them, and methods of using them.